Developer carrying member and developing apparatus

Abstract

In a developer carrying member used in a developing apparatus by means of which an electrostatic latent image formed on an electrostatic latent image bearing member is developed with a developer to render it visible, the developer carrying member has at least a substrate and a resin coat layer formed on the substrate surface, and the resin coat layer contains at least a binder resin and graphitized particles. The surface of the resin coat layer has an average value A and a standard deviation σ of 100≦A≦800 (N/mm 2 ) and σ<30 (N/mm 2 ), respectively.

1. A developer carrying member for carrying a developer, comprising:
 a substrate; and 
 a resin coat layer formed on a surface of the substrate, 
 wherein said resin coat layer contains at least a phenol resin as a binder resin and graphitized particles, 
 wherein said graphitized particles are prepared by heat treatment of particles which are optically anisotropic and formed of a single phase, in an inert atmosphere at 2,300 to 3,200° C., said particles being mesophase pitch, and said graphitized particles have a degree of graphitization p (002) of 0.20≦p (002)≦0.95, and 
 wherein the surface of said resin coat layer has an average value A and a standard deviation σ of:
   100 ≦A≦ 800(N/mm 2 ); and 
   σ<30(N/mm 2 ); 
 
 which are determined from the hardness distribution of measured values HU of universal hardness in a surface physical-property test, calculated according to the following expression:
   universal hardness value  HU=K×F/h   2 (N/mm 2 ), 
 
 where K represents a constant, F represents a test load (N), and h represents the maximum indentation depth (mm) of an indenter, and 
 wherein said graphitized particles have a volume-average particle diameter in a range of 0.5 μm to 4.0 μm, and the surface of said resin coat layer has an arithmetic-mean roughness Ra in a range of 0.20 μm to 0.70 μm according to JIS B 0601. 
 
   
   
     2. The developer carrying member according to  claim 1 , wherein said resin coat layer further contains a charge control agent for controlling the charging of a developer. 
   
   
     3. The developer carrying member according to  claim 1 , wherein said particles, which are optically anisotropic and formed of a single phase, have stacks of aromatic molecules.